.TH std::bad_weak_ptr 3 "2024.06.10" "http://cppreference.com" "C++ Standard Libary"
.SH NAME
std::bad_weak_ptr \- std::bad_weak_ptr

.SH Synopsis
   Defined in header <memory>
   class bad_weak_ptr;         \fI(since C++11)\fP

   std::bad_weak_ptr is the type of the object thrown as exceptions by the constructors
   of std::shared_ptr that take std::weak_ptr as the argument, when the std::weak_ptr
   refers to an already deleted object.

   std-bad weak ptr-inheritance.svg

                                   Inheritance diagram

.SH Member functions

   constructor   constructs a new bad_weak_ptr object
                 \fI(public member function)\fP
   operator=     replaces the bad_weak_ptr object
                 \fI(public member function)\fP
   what          returns the explanatory string
                 \fI(public member function)\fP

std::bad_weak_ptr::bad_weak_ptr

   bad_weak_ptr() noexcept;                            \fB(1)\fP \fI(since C++11)\fP
   bad_weak_ptr( const bad_weak_ptr& other ) noexcept; \fB(2)\fP \fI(since C++11)\fP

   Constructs a new bad_weak_ptr object with an implementation-defined null-terminated
   byte string which is accessible through what().

   1) Default constructor.
   2) Copy constructor. If *this and other both have dynamic type std::bad_weak_ptr
   then std::strcmp(what(), other.what()) == 0.

.SH Parameters

   other - another exception object to copy

std::bad_weak_ptr::operator=

   bad_weak_ptr& operator=( const bad_weak_ptr& other ) noexcept;  \fI(since C++11)\fP

   Assigns the contents with those of other. If *this and other both have dynamic type
   std::bad_weak_ptr then std::strcmp(what(), other.what()) == 0 after assignment.

.SH Parameters

   other - another exception object to assign with

.SH Return value

   *this

std::bad_weak_ptr::what

   virtual const char* what() const noexcept;  \fI(since C++11)\fP

   Returns the explanatory string.

.SH Parameters

   \fI(none)\fP

.SH Return value

   Pointer to a null-terminated string with explanatory information. The string is
   suitable for conversion and display as a std::wstring. The pointer is guaranteed to
   be valid at least until the exception object from which it is obtained is destroyed,
   or until a non-const member function (e.g. copy assignment operator) on the
   exception object is called.

.SH Notes

   Implementations are allowed but not required to override what().

Inherited from std::exception

.SH Member functions

   destructor   destroys the exception object
   \fB[virtual]\fP    \fI(virtual public member function of std::exception)\fP
   what         returns an explanatory string
   \fB[virtual]\fP    \fI(virtual public member function of std::exception)\fP

.SH Example


// Run this code

 #include <iostream>
 #include <memory>

 int main()
 {
     std::shared_ptr<int> p1(new int(42));
     std::weak_ptr<int> wp(p1);
     p1.reset();
     try
     {
         std::shared_ptr<int> p2(wp);
     }
     catch (const std::bad_weak_ptr& e)
     {
         std::cout << e.what() << '\\n';
     }
 }

.SH Possible output:

 std::bad_weak_ptr

   Defect reports

   The following behavior-changing defect reports were applied retroactively to
   previously published C++ standards.

      DR    Applied to          Behavior as published              Correct behavior
                       calling what on a default-constructed    the return value is
   LWG 2376 C++11      bad_weak_ptr was required to return      implementation-defined
                       "bad_weak_ptr"

.SH See also

   shared_ptr smart pointer with shared object ownership semantics
   \fI(C++11)\fP    \fI(class template)\fP
   weak_ptr   weak reference to an object managed by std::shared_ptr
   \fI(C++11)\fP    \fI(class template)\fP
